Pyrrocoline dyes



Un t d at P t n PYRROCOLINE DYES Robert 8. Long, Bound'Brook, andRichard J. Boyle,

Neshanic, N. 1., assignors to American Cyanamid Company, New York, N.Y., a corporation of Maine No Drawing. Application September 18, 1957Serial No. 684,646

3 Claims. (Cl. 260-295) This invention relates to new red pigments ofthe phthaloyl pyrrocoline carboxamide type and, more specifically, tocompounds of the formula:

in which X may be chlorine, lower alkoxy, lower alkyl, and nitro.

Compounds of this type are referred to as aromatic amides of2,3-phthaloylpyrrocoline-l-carboxylic acids. They may also be referredto as naphtho (2,3-b) pyrrocoline-6,ll-dione derivatives. However, forconvienience, the phthaloylpyrrocoline designation is used in thisspecification.

Red organic pigments of good fastness are ditlicult to obtain. In thepast, various azo compounds have been used .to obtain red shades,especially where organic pigments are desired. Azo compounds, however,lack,

as a general rule, the extreme fastness properties re-' quired forpigments. Consequently, fading has been a pronounced defect in the redpigments heretofore obtainable. The alternative of using various vatdyesas pigments is not a satisfactory substitute since the available redshades of vat dye which possess good pigmentary properties are notcompetitive in brightness with the azo compounds. There is thus a bigneed for red pigments with the brightness of azo compounds and thefastness of the anthraquinone pigments.

We have found that certain arylides of2,3-phthaloylpyrrocoline-l-carboxylic acid, namely-those of thestructure:

in which RCO-- represents the above acyl radical and in which X may beCl, lower alkoxy, lower alkyl,

or N are excellent red pigments of considerable brightness andsurprisingly high degree of light fastness.

It is most surprising that these pigments should be bright reds sincethe unsubstituted anilide is a violet which is lacking in brightness. inaddition, the unsubstituted anilide is lacking in fastness to light andit is surprising that the introduction of a nitro group has such amarked efiect on'the fastness and other pigmentary properties. Evenother amides which have a reddish self shade, suchas naphthylamides, arenot satisfactory pig meats.

By varying the substituents on the amide group within theindicatedlimits, a variety of shades of reds may beobtained, fl'fhepigments uoflthe present invention have excellent properties showdesirable bright red shades of excellent fastness. An' esp'eciallysurprising property is their striking fastness to light, all the moreunexpected since the corresponding simple phthaloylpyrrocolinedcarboxylic does-.not'have this property.

A convenient methodtor the preparation of ments of our'inventioninvolves the use, as a starting material, of the acid chloride of2,3-phthaloylpyrrocoline-l-carboxylic acid. This chloride may beprepared by the method of Pratt et al. The arylides are obtained byreaction of the acid chloride with the desired aromatic amine. Thearomatic amines which are used are all nitroanilines, there beingspecifically used, 2-

, chloro-4-nitroaniline, 2-methoxy-4-nitroaniline, Z-methylformed by'this first step,- are thenconvertedto the arylides by conversion throughthe carboxylic acid to 4nitroaniline, 2,4-dinitroaniline,2-ethyl-4-nitroaniline and 2-ethoxy-4-nitroanilinc. The presence oflower alkoxy and alkyl groups in the nitroaniline is particularlyadvantageous. In general, these further substituted nitro andappreciably greater 'ti'nctor'ial strength;

The Pratt'method of preparing thepyrrocoline caranilides have moreattractive shades; improved fas tness v boxylic esters involvesthe'condensation "of dichloronaphthoquinone with" ethyl acetoac'etate inthe presence of pyridine:

, ont-r'z-car-coocim 01 The esters-10f the phthaloylpyrrocolinecarboxylic acid the acid chloride and reaction-with the desired aromaticamine.

For the preparation of the aromatic amides, the acid chloride of the2,3-phthaloylpyrrocoline1-carboxylic acid is heated with the aromaticamine in an organic solvent; o-dichlorobenzene is an example of anespecially useful solvent for'this purpose. On cooling, the reactionproduct is isolated by ordinary means. An alterna- 1 tive methodis toreact the acid directly with the amine according to known proceduresusing a compound such as phosphorus dichloride as condensing agent.

Thisapplicationis a continuation-in-partof our copending application,Serial No.

512,888, tiled June 2, $,mowabandoncd. I Y? the pig-.

h i nti n m y be fu er fllurtrated r thcfoH ing examples: Example 1 Amixture of 100 of ruethylgaoetoaoetatqlzii p r s pYr d ne p r s of nh dous alcohol an 40 parts of 2,3-dichloro-'l,4 i1aphthoguino isheated tothe w t mp tu W irr n s bs anti ly comp e eift 'ri li si tl Precipi tsolid is collected byf filtration d washedfjthoroughly with ethanol;the' 'product which sl'obtained is purified by recrystallization fromglacial acetic acid.

Example 2 To l20 parts of ethanol is add d 12. parts of1-wbomethoxy-2,3-phthaloylpyrrocoline. h m xt re is stirred and heated,and to the hotslurry isslowly added 20 parts of N sodium hydroxidesolution. After stirring at the reflux temperature for a short time, thesolid sodium salt which precipitates is isolated by filtration. This isstirred with boiling acetic acid and the product which precipitates oncooling is collected, washed thor oughly with water, and dried.

Exaliz'ple 3 A mixture of 61.2 parts of 2,3-phtha1oylpyrrocoline-1-carboxylic acid and 640 parts of thionyl chloride is stirred at thereflux temperature until the reaction is substantially complete. Aftercooling, the solid mate rialis-ren oved by filtration and washedthoroughly with light petroleum ether. v After drying the acid chlorideis obtained as an orange solid.

Example 4 A mixture of 7.74 parts of ,2,3.-phthaloylpyrrocolinercarbonyl vehloride,i 8.4 par of 4-uitro-foranisidine and 1 30 parts ofo-dichlorobenzene is stirred .at the reflux temperature until thereaction is substantially complete.

the eact on. i

After cooling, the precipitated tion, washed thoroughly'with" alcohol,then" with hot water and finally again with "alcohol. After drying theproduct is obtained as a red colored solid. It may be purified byrecrystallization from o-dichlorobenzene. When an equivalent quantity of4-nitro-2-ethoxy aniline is used in place of the nitroanis'idine thecorresponding 4-nitro-2-ethoxy aniline is obtained.

Example 5 A mixture ofl3.6 parts of the carboxylic acidchloride ofExample 3 and 960 parts ofo-dichlorobenzene is heated to reflux. Thereis then added 7.6 parts of 2-chloro-4-nitroaniline and the mixture isheld at reflux until the reaction is substantially complete. The mixtureis cooled to 60 C. and filtered. The solid product is Washed withalcohol and dried. It can be recrystallized from trichlorobenzene.

Example 6 i OQNHQ-NO:

A mixture of 15.05 parts of the acid chloride of Example 3 and 720 partsof o-dichlorobenzene is heated to reflux and 7.42 parts of2-methyl-4-nitroaniline is added. The mixture is held at reflux'untilthereaction is'suban ial y complete d s en l d to 0. The s l product'isisolated by filtration, washed with alcohol and dried. It can berecrystallized from trichlorobenzene.

A similar product is obtained by using an equivalent quantity of2-ethyl-4 nitroaniline in place of the methylnitroanilinc.

Example 7 The procedure of Example 4 is followed using an equivalentquantity of 2,4-diriitroaniline in place of the nitroanisidine.

Example 8 solid is removed by filtraf Print Tone Tint Tone Amide ShadeFastness Shade Fastness Anilide standard (dull model-size fading.standard (violet modertte fading.

violet). y)- 4-Nitro-2-anisidide much redder trace of fading"- very muchno change.

redder and brighter. 4-Nitro-o-toluidide very much redder." do do D0.4-Nitro-2-ch1oroanilide very much brighter no change do D0.

and redder.

We claim: References Cited in the file of this patent 1. The2-chloro-4-njtroanilide of 2,3-phthaloylpyr- UNITED STATES PATENTSrocoline-l-carboxylic acid.

15 2' The z y i fli of p py 2,772,274 Schmrdt-Ngckels 6t NOV. 27,rocoline l carboxylic acid. 2,773,873 schmldt-Nlckels et a1. Dec. 11,1956 3. The 2-methyl-4-nitroanilide of2,3-phtha1oy1pyrrocoline-l-carboxylic acid.

1. THE 2-CHLORO-4-NITROANILIDE OF 2,3-PHTHALOYLPYRROCOLINE-1-CARBOXYLICACID.